BEW into B6 S4

nitec

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Jan 30, 2006
Location
Ottawa, ON
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1.9TDi PD
Folks,

I`m about to get ahold of a gorgeous S4 avant manual with some engine difficulties. I have been looking for a B6 avant body to swap my BEW into but always thought it would be a 1.8T...

My first thought was this is going to be easy peasy...but then I started reading about CAN bus etc...Assuming 1.8T engine mounts will work into the B6 body and the tranny (6 speed close ratio) will mount to my BEW, what are your thoughts on making the electrical work? I`m more than comfortable with the job but is the CAN bus going to cause issues? Would it be more complicated than swapping the ECU and harness and adapting to the B6? Would I need to get a different cluster etc?

This is a bit of a time sensitive question - any help is appreciated...
 

oilhammer

Certified Volkswagen Nut & Vendor
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Dec 11, 2001
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outside St Louis, MO
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There are just too many to list....
A BEW car has a CAN bus, too. People have done this type of swap, I'd think it would not be too difficult BUT you may want a diesel-specific cluster.

BEW engine would NOT be the best choice, though. BHW would be much better, as very little of the BEW's bits will actually work in the longitudinal engine bay, you'll need to change a LOT of stuff. Besides the BHW is already gifted with 36% more hp and nearly 250tq already, and comes from a car that is very closely related to the S4 (they rolled off the same assembly line).
 
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nitec

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Ottawa, ON
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hmmm...my 2004 jetta seems to disagree on the can-bus thing...I`ll have to check closely - looks like the MK5s are all can-bus so maybe mine is too on account of being the last of the MK4s

as for the engine - it's coming out of my daily MK4...the previous owner used a ski box and as a result there are rust holes in my roof - not spots...holes...yes - water is leaking into my car :( so before the whole thing falls apart I started looking for a B6 avant to swap the engine into...I`m not too worried about the accessories per se - everything will be custom anyways...

so this 2004 S4 popped up at a good price due to engine problems...I have no desire to drive a V8 but damn the rest of the car is gorgeous...
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
The term "CAN bus" is pretty misleading, so let me clarify. Starting in 2000, the Golf, Jetta, and Beetle got an early CAN system. They use a CAN Gateway (accessible via VCDS) that uses the typical paired wire data bus, connecting most of the various modules. 1999 and older versions of these models were still using the single K-line.

The protocols for CAN changed again on the 2004 models. I don't know the exact specifics, but I know the old VCDS HEX-USB cable won't work on my 2004 Passat, I had to use my HEX-CAN cable.

Then on the A5 chassis Golf/Jetta, they changed some protocols again. Some of the changes have to do with baud rate, others have to do with the addition of more modules. For instance, the 2000+ A4 models' Comfort Module communicates on the CAN bus, but it has its own seperate "mini network" for the door modules, with its own dedicated paired wire system that is not connected to the main bus. The A5, they all work in tandem.

There are other changes later, and the NMS Passat is even more complex, as they have done what MB has been doing for years, and gone to a layered CAN bus system, with different speeds for different uses. So on my 2000 Golf, my ABS module and SRS module must share communication routes with more plebian things like the radio and engine controller. The newer cars they have seperated that out.

FWIW, the CAN system was invented by Bosch, with help of a little-known-at-the-time company called Intel. It was originally formed for use in production line computers, but a few years later MB realized their new replacement for the W124 S-class, the W-140, was going to be FAR too complex for the technology at the time. So when that car debuted, the Bosch CAN system was put into use. It has since spilled out into many German cars, and a few years ago SAE decided that it was the best protocol to use in automotive systems, so it is essentially mandated now, but there are some variations.
 
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